Garcia Eduardo, Nikolic Damjan S, Piguet Vincent
Department of Dermatology and Venereology, University Hospital and Medical School of Geneva, 1211 Geneva, Switzerland.
Traffic. 2008 Feb;9(2):200-14. doi: 10.1111/j.1600-0854.2007.00678.x. Epub 2007 Nov 22.
Dendritic cells (DC) are crucial components of the early events of HIV infection. Dendritic cells capture and internalize HIV at mucosal surfaces and efficiently transfer the virus to CD4+ T cells in trans through infectious synapses (trans-infection pathway). Alternatively, HIV-1 replicates in DC (R5-HIV-1) (cis-infection pathway). Here, we analyzed HIV trafficking in DC during the trans-infection pathway as well as the cis-infection pathway. Confocal immunofluorescence microscopy demonstrated that after capture by DC, R5-HIV-1 and HIV-1 pseudotyped with vesicular stomatitis virus protein G colocalized in a viral compartment enriched in tetraspanins including CD81, CD82 and CD9, although at different levels, indicating a role of the viral envelope in targeting to the tetraspanin-rich compartment. Replication of R5-HIV-1 in DC (cis-infection pathway) also led to the accumulation, in an envelope-independent manner, of mature viral particles in a tetraspanin-rich compartment. A fraction of the HIV-1-containing compartments appeared directly accessible from the cell surface. In sharp contrast with the trans-infection pathway, the delta-subunit of the adaptor protein 3 (AP-3) complex was enriched on the HIV-1-containing compartment during R5-HIV-1 replication in DC (cis-infection pathway). Downregulation of AP-3 delta-adaptin reduced significantly viral particle release from HIV-1-infected DC. Together, these studies demonstrate a role for AP-3 in HIV replication in a tetraspanin-rich compartment in DC and contribute to the elucidation of the trafficking pathways required for DC-T cell transfer of HIV-1 infection, a critical step during the early events of HIV infection.
树突状细胞（DC）是HIV感染早期事件的关键组成部分。树突状细胞在黏膜表面捕获并内化HIV，并通过感染性突触（转染途径）有效地将病毒跨膜转移至CD4⁺T细胞。另外，HIV-1可在DC中复制（R5-HIV-1）（顺式感染途径）。在此，我们分析了转染途径以及顺式感染途径中HIV在DC中的运输情况。共聚焦免疫荧光显微镜检查表明，DC捕获R5-HIV-1和用水疱性口炎病毒糖蛋白G假型化的HIV-1后，它们在富含四跨膜蛋白（包括CD81、CD82和CD9）的病毒区室中共定位，尽管程度不同，这表明病毒包膜在靶向富含四跨膜蛋白的区室中发挥作用。R5-HIV-1在DC中的复制（顺式感染途径）也导致成熟病毒颗粒以不依赖包膜的方式在富含四跨膜蛋白的区室中积累。一部分含有HIV-1的区室似乎可直接从细胞表面进入。与转染途径形成鲜明对比的是，在DC中R5-HIV-1复制（顺式感染途径）期间，衔接蛋白3（AP-3）复合物的δ亚基在含有HIV-1的区室中富集。AP-3 δ衔接蛋白的下调显著降低了HIV-1感染的DC释放病毒颗粒的能力。总之，这些研究证明了AP-3在DC中富含四跨膜蛋白的区室中HIV复制中的作用，并有助于阐明HIV-1感染的DC-T细胞转移所需的运输途径，这是HIV感染早期事件中的关键步骤。
